There have heretofore been proposed electronically controlled throttle position controllers for electronically controlling the position of a throttle valve by driving a brushless DC motor depending upon the amount that the accelerator pedal is depressed (see, for example, JP-A-6-94151 and Japanese Patent No. 3070292). According to these devices, a motor driving current is supplied to three-phase stator coils wound on a stator core of a brushless DC motor in response to an accelerator position signal output from an accelerator position sensor that detects the amount that the accelerator pedal is depressed (accelerator position) to drive the brushless DC motor, whereby the position of the throttle valve is controlled, and the air is taken in by an amount that is controlled to be an optimum amount by the combustion chambers in the cylinders of the engine. The throttle position controller includes, as shown in FIG. 20, a throttle position sensor (e.g., Hall IC, etc.) 101 that detects the throttle position corresponding to the rotational angle of the throttle valve in order to control the position of the throttle valve. The throttle position controller, further, includes a rotor position detector (e.g., Hall IC, etc.) 104 for detecting the rotational position of the magnet rotor in order to control the position of the magnet rotor having field poles constituted by a plurality of permanent magnets relative to the three-phase stator coils 103.
A valve position controller 105 controls the position of the throttle valve so that there is no deviation in position between the throttle position signal output from the throttle position sensor 101 and the accelerator position signal output from the accelerator position sensor 102. The rotor position detector 104 further transmits the data to a motor driver 107 through a rotor position detector 106 so as to vary the amount of motor driving current to the three-phase stator coils 103 and to vary the direction of the current. The rotor position detector 106 detects the position of the magnet rotor relative to the three-phase stator coils 103, so determines the motor driving current selectively fed to the two phases of the three-phase stator coils 103 that the magnet rotor produces a maximum output torque depending upon the detected result and, further, determines the direction of the motor driving current fed to the three-phase stator coils 103.
However, the above throttle position controllers include the throttle position sensor 101 for controlling the position of the throttle valve in addition to including the rotor position detector 104 for controlling the position of the magnet rotor relative to the stator coils 103 and the rotor position detector 106, posing a problem of an increased number of parts and boosting up the cost.